What conflict develops between the trenglos family and the gunliffes

The main conflict that develops between the Trenglos family and the Gunliffes is the fact that they cannot decide who has authority over the cove. Both families want to benefit from the seaweed that can be harvested there. However, as the cove has no owner, they both want to control it. When Mally refuses to sell seaweed to the farmer Gunliffe, he send his son to harvest it, which angers Mally greatly.